Lenses and their combination and arrangement in various instruments and apparatus



Filed Jan'. 27, 1934 La AT rfi May 21, 19.35... ,H. J. -BxRcHALL 2,901,952'- LENSES AND 'THEIR 'COMBINATION ND ARR-XHGEMENT l v IN-YM-OUS INSTEUQENTS AND PARAUS Filed Jan. 27, 1934 2 Sheets-Sheet 2 2 Claims. .The invention relates .to ranges anderen to their combination and arrangement in various instruments and apparatus and provides the hereinafter Q A'described and claimed improvements;

Q5 'The object of the invention is toprovide a lens having gradually varying focallengths between two extremities or points ofits surface, that is to say, without visible break er step' throughout the range.

10 A lens according to the invention has a surface g' whose curvature has the characteristics of a segment' of a. solid or hollow geometrical cone, that 5' is to say, the radius of curvature of said surface E progressively changes, inthe same way es a cone 5 segment', `oetvveen two extremities or points on i said surface and equally each side the axis of the lens, which .axis is intended in this specification to conveys:A medial'lne along the surface of the lens and which lnedial line is radial of the cone. i)- formation cf which the segmentforms a' part, and will 'oe hereinafter reerredto as the principal med-iai line. i Such a lens has definite uses as will-be hereinl after described, as for instance, when two 'are v5 arranged as a pair with coincident principal medial lines but reversely disposed and arranged. for adjustment along said medial lines.

The invention also embodies a lens having .characteristic curvings of a. cone segment in one 0 direction, as aforesaid, but also having en additional curving in a direction at right-angles, that is to sayin the direction `of the principal medial line, Whi'cnaddit-ional curving preferably varies progressively to the extent of a nui-nner of diep- ;5 tersoi difference between two points in 'such direction. This additional curving, in thedirection of the medialflinc aforesaid, is so combined with the curvings across the medial line .that a. single lens can be used as a. spectaclelens in substitu- 0 tion for the ordinary bi-focal lens-to gi-ve gratin ally varying focal' lengths, es for instance, lietween distance and reading, Without. any visible break c: .ep throughout the ruige'. r TWG oi 'Such lenses maybe used as a pair in an instrument or apparatus for various purposes,

being placed with their medial lines coincident but reversed 'as to their ends. and arranged to adj-ust' upon e'ach other parallel to'said medial second form of the 'invention provides a lens which might be regarded as having a surface :somewhat similar to a curveesidecl c'one, but 'the curvature in the direction oi the medial line is 5 preferably a particular' curvature combined with i FFICE v v vLenses 'einem 'cennnm'rrorr mm snnlnvcemr nv .veulens "rNsrnU- i I ivrezvrs AND APPARAIUS .Henry .lames Birehail, 55,11'11'315, K' v @privation January 2x1-esegesi@ No. 'ies-,ssa In Great Britain December' '-14, 1932 the particular conefglcurvfatulre els described reieence .to the first form of lens.

The surface of the se'e'ond described lens' could conveniently be produced if a cone segment ol the nrst formof lens were. ground simultaneously in both directons *at right-angles by the' inner surface of a strai'ghteslcled .revoluble cone which grindsv both the cone curvings and the medial line curv-ings, the latter'hevever being controlled by a former; but in commercial prnduction'these cu-wings would 4be obtained simultaneously from a glass piece.

'The invention will be more clearly understood? by the description hereinafter appearing with reference to the accompanying diagrammatic drawings which are 'by-way oi example only.

Fig. l is a iront elevation of a lens having a surface characteristic of a segment of a cone,

Fig. 2 to Fig. 2d is a series of transverse sections l of Fig. 1 taken at the positions indicated by the dotted lines.

Fig. 3 isa side elevation of Fig. l.

Fig. 4 is an elevation of je. combine-tion of twopairs oi lenses applied at right-angles -to each other' and which would be'mounted for use Vin an.

instrument' or apparatus.

Fig. '5 is amend elevation or Fig. 4. Fig. 6 is a diagrammatic View illustrating the .manner in which a segment is taken'irozn a cone .of su-ch lensesjapp'lied longitudinally ,to each other vfor use in instruments or apparatus.

-1l is a transverse sect-ion of Figi v10 wher-ein the vlenses are placed to provide minimum magnification.

Fig. 'l2 is a transverse :sec-tion of 1D wherein the lenses are placed-to provide maximum magnication.

Fig. 13 is 'a diagrammatic perspectlveview o! a machine for forming the suriaceof this form of lens. n

The numeral-l indicates 's lens .according to the inventionvehleh is vco'nzei'ilentiv illustrated-a5 being square 'out which-'may benny'other desirable shape.- -A "surface 2 of this lens i-sjformed -in a. manner-having the characteristics of the surface of e. segment 'of a cone, i. e., niong the principal medial line AB fand in all @lianes .parallel theres.

with 'the surface 2 ci! the lens is as illustrata ed ln Fig. 3 while .along the medial line CD, at rightangles to -t'ne medial-line AB, and in planes paralleltherewlh 4the surface o! the lens constantly curves in progressiveradii' extending along theniedial line f-.B as illustrated in Fig. 2.

Referring tc Figs. l and 2 ,the radius of curva., ture at the position 2,-2 of Fig. 1 is shown in the corresponding sectional view in Fig. 2, and the radius .of curvature at Athe position 22".ot Fig.

1 is valso'l shown in the corresponding 'sectionalv view in Fig. 2l and similarly the radii of curvature at the positions 2li-'2b. 21-'2c and 215--2'x are also shown in the corresponding sectional views in Fig. 2. As can be clearly seen by Fig. 2 the surface of the lens constantly curves in planes parallel to the medial line C21-Din progressive* "illustrstedas, lacing plane, but would be formed in any of the convenient manners known lor variations required in optical work.

Referringv to Fig. 4 two such lenses, 4 and 5, are placed upon each other with their plane surfaces 'adjacent and their principal medial lines lparallel and coincident, but with the'grcater curvature end 'of one lens 'adjacent the .lesser curvature' end'Y of the other lens. A similar pair of lenses, 6 and l, arranged in a like .inanner,l is yapplied to the pairof lenses aforesaid with the principal medial lines of the two pairs of lenses at rightearigles to each other, the EF of the combination of the lenses' being. at the intersecting point of Vthe principal medial lines of the two 'pairs of lenses. Thepeir's of lenses and 6., l are mounted in such a man ner that each pair or all .collectively 'are adjustable in e. direction parallel to .their principal medial lines, .to thereby vary the focal length of the combination of the lens at theaxis thereof and provide the effect -of a variable spherical' lens. cylindrical lens would result.

Fig. 5 illustrates the same .arrangement as Fig. 4 but in end elevation whereby the directionl in which tire pair voI-.lenses l's-nd 5 is `adjusted can clearly be seen.

Fig. 6j illustrates a means of obtainingl n lens according to this form of the .invention wherein a glass'cone 8 is ladapted to have'rernovedtherev :frein a segment 8.

Figs. `t7--9 illnstrate a :lens in according to the second form of the irentlon, particularly intended. vfor use in spectacles. The surface il of this lens varies in progressive curvature along "itsprincipal medial line' GH and in planes parallel'thereto to the verr-tent o! anuniber. of di?" opters of dilerence between any twopoints along lsaid surface in'such direction as clearly illustrated in Fig. 9, while'in a direction along -the medial line IJ, at rightaang-les to the medial vline GH, and in all planeslparailel therewith the surface oi' the lens constantly .curves in progressive radii extending along the medial line GH', in a manner characteristic of the surface of a segment of a. cone. This is lclearly illustrated in Figa!! to 8l where the sectional views respectively show the curvature of 4the lens acrossthe positions indicated by 8,8, Mv-8*, 8th-.8", Btl-8 In the case of one ypair only a vari-ablev and l8e4-8, The .variations of curvature rnc! be between any .two points 4for instance, between' the points .20. '21, shown in -broken lines-Fig. 7,.

and'constent from these points to the extremities The invention in this form therefore provides a lens which.A in one direction parallel to the principal medial line, the focal length progressively' varies, while .at right-anglesio :and .e'x-

tending along said principal mediallinelthe localf length also progressively varies.

between .the extremities of two diil'erent'sightings The efect o( such lenses in spectacle5lsthat- 'a 4as for distance above and reading below there is such a' variation in curvature that 'the change is extremely gradual as opposed to abrupt with all the advantages accruing' from this gradual change in vboth directions and without the obec'lionable features present in spectacles having bi-focal lenses. It-willhe :clearly-understood that I given a lens with a surface according to this form of the invention the other surface thereof may be formed or worked up in any convenient manner knownior-variations required in optical work.

Fig. l0 illustrates afcomhinationfo! two of such lenses according to this form of the invention viz. l2 land i3 placed -upon eac-h other withtheir ,plane surfaces H adjacent and 'their'principal medial lines parallel and coincident.' but .with .the greater curvature end of one lens adjacent the lesser curvature end of the other lens. This pair of .lenses is mounted in such a `manner that J -one or both collectively arc -ndjnstabi-e in a direction parallel to their principal 'lne-dial lines, to thereby vary the lfocal length of the combination at the axis thereof, 'and provide the effect 0f vvariable spherical lens.

The lens' according to this second invention is therefore 'substantially ofthe same progressive power cach side the principal rncdie-l line as it is on 'scid principal 'nie'dal line and to the .full extent of the progression.

The lens according to the second `iorrn of the inventioncan oe produced in various ways. but one machine for the purpose is illustrated in 13 and comprises a hollow cone i5 revoluhle about its axis M. N. combined with ai transverse carrier 7 .carrying the lens i8 and'attached. at each endA to-lormers Ai8 hav'ngjworkng .under surfaces which are an exact shape ,replicazoi .the lens to be produced in the direc-tion of the prin-l -cpal lmedial line, these two-.formers rolling of the 'invention has extensive .use -i-or spectacles and .also uses as a pair-in an instrnrnentor appliance as -for instance 'for vthe purpose oi eye-- sight testing and correction. the lens according to the ilrst foi-rn of the inventionls principally of value when .a pair is' used or. two-pairs are usedV in an instrument such as @would beu-senil {o1-.the purpose-of eyesight testing and correction.

Having now described my invention. what I claim and desire to secure-byLettcrs Patent l. A pair ci 'lenseseech having s 'suriacewhich in one of two' directions' at Arightfilngl-es,

While the lens .according 'to the second i'orm form of the' l 40' i l i l varies 1n rogressive curvature to the .eent'of a number QI diopters or cii'erence 'be-Weer. .two

v points aion'g vsaid.sr1x'fx a. ce, and also which inthen'ther dirctian A :or'1.,f. txa.nt1y curves .in prngressive `ahrup't. change, in which theprincipal fase of the lens is formed with a cu'nfedisurmce whose lines-ot intersection with planes at ri .t angie:

to said sur-ieee .am Leibe principal meigl line vm progressively as "the plane o! fseetion imov in the direct'ionlci said medi-ai' gine, vte ille-relay simulate the isu'rae'e o! a s trei'ghtsided feone. while the Vhnezmif 'imtersectien with planes aff-righi eagles to the srface and paraiiel to the seid media! line are all substantially alike and cach o! progressively varying eurvture, to thereby slmulte'invoiuwrial verwies,v the back .surface 'o1 the lnsgbeiiagleft without deniteshapinx for subsequept'shapmg to cm-bine'with 'the en we pri-'rimpel surface bo eompie' ythefprescrip'- tin of :lens to the nennst-s requirements.

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